The present invention is related to an operation device which is used in an car audio system and which performs the switching of input operations by the so-called see-saw method.
An operation device which performs various kinds of switching operations is provided, for example, in a control panel of a car audio system. This type of device is provided with a depressable button (hereafter simply called xe2x80x9cbuttonxe2x80x9d) for performing the switching of input operations by the so-called see-saw method between two functions such as fast-forwarding or reversing a cassette tape. Furthermore the button of the operation device is formed so as to be illuminated from the rear so that the button is visible in darkness.
A conventional device will be explained below with reference to the accompanying figures. FIG. 22 is a schematic perspective view of a conventional operation device. FIG. 23 is a plan view of a button. FIG. 24 is a lateral view of button. FIG. 25 rear view of a button. FIG. 26 is a lateral view of a button. FIG. 27 is a cross sectional view along the line 27xe2x80x9427 of FIG. 23. FIG. 28 is a cross sectional view along the line 28xe2x80x9428 of FIG. 22. FIG. 29 is a cross sectional view along the line 29xe2x80x9429 of FIG. 22. FIG. 30 is a cross section view of the operation of a button.
In the figures, reference numeral 31 is a button which operates a switching input operation by a see-saw operation and is formed in a box shape with an aperture 31a. The button 31 is formed by a transparent resin. 31b is a flange which is formed on the outer edge of the aperture 31a. 31c is a cylindrical spindle which acts as a point of support for the see-saw operations. The spindle 31c projects so as to co-planar with the surface of the flange 31b from both sides of the button 31 and is maintained in free rotation by the maintaining sections 33a, 35b to be discussed below. 31d is a notch which is provided in the flange in proximity to the spindle 31c. 32 is a printed wiring board, 33 is a button depression section, 33a is a maintaining section which is provided at a position which corresponds to the notch 31d of the button depression member 33 and which supports the spindle from below. 34 is a cushion member which returns the button 31 to a pre-operational position after operation. 35 is a decorative panel, 35a is a button through hole which allows the passage of the button 31, 35b is a maintaining section which together with the maintaining section 33a supports the spindle 31c in free rotation. 36 is a switching element which is depressed by see-saw operations of the button 31. 37 is a lamp which illuminates the button 31 from the rear.
The operation of the invention will be explained below.
As shown in FIG. 30, when a button 31 is depressed in the direction of the arrow in the figure, the button 31 inclines by rotating about the spindle 31c. In doing so, the flange 31b pushes the cushion member 34 which undergoes elastic deformation. On the other hand, when pressure is applied to the switch element, a defined input operation is performed. When pressure is no longer applied to the button 31, the button is pushed back due to the rebounding force of the cushion member 34 and returns to a pre-operational position.
The button 31 is illuminated by a lamp 37 during operations in darkness and so its visibility is ensured.
Another conventional example will be discussed below.
FIG. 31 is a component figure of another conventional device. FIG. 32 is a plan figure of a button. FIG. 33 is a lateral figure of a button. FIG. 34 is a rear figure of a button. FIG. 35 is a lateral figure of a button. FIG. 36 is a cross sectional view along the line 36xe2x80x9436 of FIG. 32. FIG. 37 is a cross sectional view along the line 37xe2x80x9437 of FIG. 31. FIG. 38 is a cross sectional view along the line 38xe2x80x9438 of FIG. 31. In the explanation below, those components which have already been explained are referred to by the same reference numerals and their explanation will be omitted.
In the figures, reference numeral 41 refers to a button which performs switching input operations by a see-saw operation and is formed in a box shape which has an aperture 41a. The button 41 is formed from a transparent resin. 41b is a flange which is continuously formed along the outer edge of the aperture 41a. 41c is a cylindrical spindle which is the point of support for see-saw operations. The spindle 41c projects so as to be co-planar with the surface of the flange 41b from both sides of the button 41 and is maintained in free rotation by the maintaining sections 33a, 35b. 
The operation is the same as the first conventional example which has been explained above and so will not be repeated.
Since the conventional operation device is constructed in such a way, in order to maintain the operation space of the maintaining section 35b when the button 31 is operated, a notch 31d must be provided on the flange 31b. Thus the problem arises of light from the lamp 37 escaping from the notch 31d. 
Furthermore in order to perform smooth see-saw operations, it is advantageous that the spindle 31c is formed with a small diameter, and the frictional resistance of the maintaining sections 33a, 35b is reduced. However in consideration of the rigidity of the spindle 31c, the effective minimum diameter is limited which thus increases the problem of reducing frictional resistance.
Furthermore returning the button 31 after the switching operation to an initial position requires a separate operation of the cushion member 34. Thus this entails problems of an increased number of components and assembly operations as well as increases in costs.
Since the conventional device is constructed as above, although it is possible to prevent light of the lamp 37 from escaping by a flange 41b formed on the entire circumference of the button 41, the problems have arisen that the spindle 41c of the button 41b projects more than the flange 41b and that the outer diameter of the button 41 is increased. Tokkai-Hei-9-223437 discloses a conventional device with the object of preventing light escaping without inhibiting the miniaturization of the device.
The present invention is proposed to solve the above problems and has the object of providing an operation device which can reduce escaping light when a button is illuminated, which allows the miniaturization of the device. The present invention also allows the smooth performance of the see-saw operation of the button.
The present invention allows a button to return to a pre-operational position after a switching input operation without the use of a separate cushion member which allows a reduction in costs.
The present invention comprises an outer support section which projects towards an outer face of said button, an inner support section which projects towards an inner face of said button, a maintaining section for said outer support section which is provided on a front wall face and which maintains said outer support section in free rotation, and a maintaining section for said inner support section which is provided on a button depression member and which maintains said inner support section in free rotation.
In this way, rigidity may be maintained and a smaller outer support section than the conventional device may be formed. Thus it is possible to miniaturize the device and smoothly perform see-saw operations.
The present invention employs a cushion member which is provided on the button depression member as a button return member.
In this way, it is possible to return the button to a pre-operational position with a simple structure.
The present invention uses an elastic piece which is integrated with the maintaining section of the button depression member as a button return member.
In this way, it is possible to reduce the number of separate components such as the cushion member, to simplify assembly procedures and to reduce costs.
The present invention provides an illumination element which illuminates the button of an operation device, which is provided with a cushion member, from the rear. The illumination element is provided on a mounting board. A flange is provided which is continuous with the outer edge of the aperture of the button.
In this way, it is possible to reduce escaping light.